THE MAJOR ENVELOPE GLYCOPROTEIN OF THE EXTRACELLULAR VIRION OF AUTOGRAPHA-CALIFORNICA NUCLEAR POLYHEDROSIS-VIRUS POSSESSES AT LEAST 3 DISTINCT NEUTRALIZING EPITOPES

A panel of monoclonal antibodies (MAbs) to the extracellular virion (E CV) of the baculovirus AcMNPV was developed and characterized. Four of the MAbs recognizing the major glycoprotein gp64 neutralized infectiv ity. Further characterization of these neutralizing MAbs indicated tha t they recognize epitopes distinct from those recognized by a previous ly characterized neutralizing MAb to gp64 (Volkman et al. (1984) Virol ogy 133, 354-362). Two of the neutralizing antibodies in our panel rec ognized gp64 on western blots. Neither neutralized infectivity after l imited proteolysis of gp64 with either trypsin or Proteinase K. Both o f these MAbs recognized a 24.6-kDa peptide following partial digestion of gp64 with V8 protease. Two additional neutralizing MAbs recognized disulfide-linked oligomeric gp64 as well as a monomeric form in which at least some intramolecular disulfide bonds were present. In additio n, both MAbs continued to neutralize infectivity of ECV following incu bation with either trypsin or Proteinase K, indicating that the epitop es recognized by these monoclonal antibodies are retained by the 34-36 kDa protcolytic fragment. These results, indicate that gp64 has at le ast 3 distinct neutralization epitopes, two of which are recognized by our MAbs and one which is recognized by the previously described MAb.